This invention relates to a thermal compress capable of being heated or cooled by various energy sources without the compress construction being adversely effected.
Compresses have been used to apply heat or cold therapy to human or animal body parts. The previous known compresses used polymer gels because of the high relative heat capacity of these materials. The gels are flexible allowing for better heat transfer ability to body parts. Unfortunately, the previous compresses are unwieldy to store because the gels are prehydrated. Some of the compresses use water as the internal fluid. While the heat capacity of water is relatively high, these water filled compresses can not be reused a great number of times due to potential leakage from the compresses.
Thermal compresses including a plastic envelope containing a gel capable of maintaining its gel-like consistency over a wide temperature range are known as evidenced by U.S. Pat. No. 3,885,403, granted May 27, 1975, and U.S. Pat. No. 4,756,311, granted Jul. 12, 1988. Hot and cold compresses including a rupturable container constructed of a laminated plastic sheet material and an outer layer of low density polyethylene are disclosed in U.S. Pat. No. 3,763,622, granted Oct. 9, 1973. Hot and cold compresses including containers or envelopes formed from laminated plastic sheets are also disclosed in U.S. Pat. No. 3,893,834.
In the gel based therapy device of U.S. Pat. No. 4,671,267, a pre-made mix of a humectant or moisturizing agent with a polymeric matrix is enclosed in a water impervious fabric. Heat or cold is applied to the U.S. Pat. No. 4,671,267 gel based therapy device and the therapy device is applied to the body part. The polymeric matrix maintains its gel qualities after use.
Other compresses have used gels for their heat capacity qualities. In the U.S. Pat. No. 4,756,311 microwaveable thermal compress, the gel is completely sealed in an envelope. The thermal compress can be microwaved and then applied to the body part for warming. Since the gel is sealed in the envelope, the gel is pre-saturated. As a result, storage of the compresses is cumbersome making repeated reuse of the compresses undesirable.
The instant invention thermal compress as disclosed herein is capable of various uses such as to warm body parts or to cool an injured part of the body. Most compresses currently being manufactured in the United States are made from sheets of plastic or from tubular extruded plastic. The plastic layers are sealed to form a closed envelope. The envelope is filled with a gel-like substance that can withstand temperatures without decomposing or losing its viscosity. Methods of heating the compresses include placing the compress in hot water, or placing the compress into a microwave oven. The compress is cooled by placing the compress in the freezer compartment of a refrigerator. During these methods the gel is put under stress and can lose its viscosity. This causes the compress to have erratic performance. The compress plastic also loses its strength with repeated use.